Friday, January 27, 2023

Using Laser Engraver, Plywood, and Poor Quality Control

I've had some rOtring drafting implements (pencil and pen) that I wanted to protect a little more than having them bounce around in a drawer all the time.  It dawned on me that I have the resources I need for a custom kit box.  I opened lightburn, and sketched out my pencils/pens and some old (albeit rusty) compasses that I'm going to clean up.

The next step was to load this into the laser cutter and make a run at cutting this out.  I used 1/4" plywood from some random store that had orange markings (Dome Hepot, I think is the name).  I set it up, and cut three out (and two solid with just the outline).  I started with a single pass at 20mm/s and 100% power, and counted the passes required to get through the material.

 It took 15 passes at 20mm/s and 100% power to "get through" the plywood.  So, I loaded the lightburn up again, and changed the cut to repeat 15 times, and started it off again.

When I pulled everything off and flipped the board, I found that it did not cut all the way through in some places.  Further check confirmed that the 1/4" plywood was shallow in some areas 1/32", and it was thick in some areas by 1/32".  In other words, this material was up to 1/16" out of parallel.


Oh, the lack of quality control, all to make a buck.  Next time, I'll just order some real wood from Amazon in 1/4".  I think I'll have better luck.


After the irritation subsided enough for me to break out the hobby knife, I finished the final 1/16" cuts, and pulled the parts together.  I glued two templates and the bottom together, and one template and the other panel together, and then loaded the "boards" under a portable tool set for the weight, and gave it a few hours to get up.

Once out, I just HAD to check it.

This will work.  I used a 1/8" router round over bit to round the edges, did a quick sanding job, and threw stain (dark walnut) on the two halves of the clam shell, and gave it a coat of lacquer.  I also took some dark blue felt for a machinists' tool chest and fed that through the laser engraver, too (two pieces - well, three in case I messed one up).

With them looking pretty much perfect, it was time to glue them into place. I used 1/4"-20 hex nuts as spacers to allow weight to keep the felt down (my old Digital Fundamentals college text book, and my old welding text book as well, were about perfect sizes).  I only did one piece per clam shell half in order to keep myself from getting too stressed, and added the weight/book, and waited before doing the other piece.

I tossed in the merchandise just to see how it looked :

It will do nicely.  I ordered some oiled bronze hinges and a small latch (for a jewelry box).  I cut some space in using an X-acto knife for hinges, and then put it together.

 I guess I have to clean those compasses next.  I'm not sure the best way to proceed, maybe I'll take a stab at a rotary tumbler used for rock polishing, or maybe I'll actually put in the work to polish them using the wheels on the grinder.

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